I wish to thank you all for the information and support that I have received from people posting on this site.
I have taken on board a lot of the advice offered such as the importance of having decent quality supplements, something that has really made a difference.
I must mention one particular probiotic that is guaranteed to reach the intestines without being destroyed. It contains spores which are far more robust than live bacteria.
The effect on me has been similar to that of watering a wilting plant. I feel great.
Thanks again to all of you.